The goal of this research is to develop PCR-amenable microsatellite markers from approximately 110 RFLP probes and to localize approximately 320 genetically mapped probes to chromosomal regions. The new microsatellite markers will be placed on the genetic map to ensure that they are tightly linked to the original RFLP probes. Mapped RFLP probes are an important tool for research in areas such as mapping genetic disease genes and studying loss of heterozygosity in tumor cells. The advantage of converting RFLP probes into PCR-amenable microsatellite repeat markers is two fold. First, the markers will be much more informative. Second, PCR-based genotyping methods are a significant improvement over currently used genomic Southern hybridization methods. The PCR markers can also be used as STSs for constructing physical maps for human chromosomes, for diagnosis of genetic diseases and tumors, and for identity testing. Correlation between the genetic and cytogenetic maps will facilitate localizing disease genes and genes involved in cancer. The probes that are localized to medically important regions can be used to develop fluorescence in situ hybridization (FISH)-based diagnostic tests. In addition, determining the physical location will greatly increase the marketability of probes as evidenced by the numerous questions that our Probe customer Service has received. It will also allow us to pursue the clinical market in the future.